Fer"rule (? or ?; 277), n. [Formerly verrel, F. virole, fr. L. viriola little bracelet, dim. of viriae, pl., bracelets; prob. akin to viere to twist, weave, and E. withe. The spelling with f is due to confusion with L. ferrum iron.] 1. A ring or cap of metal put round a cane, tool, handle, or other similar object, to strengthen it, or prevent splitting and wearing.

2. (Steam Boilers) A bushing for expanding the end of a flue to fasten it tightly in the tube plate, or for partly filling up its mouth.

• A metal band or cap placed around a shaft to reinforce it or to prevent splitting.
  
• A bushing for securing a pipe joint.
  
• In billiards, the plastic band attaching the tip to the cue.
  
• In painting, the pinched metal band which holds the bristles of a brush to the shaft.